I think it's possible we're not sure what you want to do! If you want to connect the printer to just one of the computers and then share it as a shared printer - Yes, that will work. And if your router has a connector for a USB printer on it - yes that will work.
I think the confusion comes in when you say through the router - as if you can just plug a serial adapter into the router or something - No, that won't work.
The other possible point of confusion - your Speedstream is in fact a router and both computers are peers on the network and get local IP addresses from the router? If this is true, yes, you can share a printer from one computer to the other.
Hope this helps.
If you need more help setting up, ask.